The present invention relates generally to a method and an apparatus for detecting tape termini in a tape recorder, and more particularly, to a method and an apparatus for detecting the starting and ending points of a tape by checking the rotatory states of a take-up reel and a supply reel.
A video tape recorder ordinarily performs an automatic rewinding function such that if a tape is completely wound on the take-up reel in a reproducing mode, that is, the end of the tape has been reached, the tape is automatically rewound onto the supply reel, and once the rewinding is complete, that is, the tape is at the starting position again, tape operation stops. To perform such an automatic rewinding function, a transparent section of tape, called a lead tape, is secured to the opposite ends of a length of video tape. A tape terminus detecting circuit is utilized to check for light-transmission through the tape, which travels between a sensor lamp and a photo-transistor, thereby detecting starting and ending states of a tape. More particularly, a light signal emanating from the sensor lamp is received by the opposingly situated photo-transistor via the transparent lead tape section, thereby detecting the start or end of a tape.
However, the tape terminus detecting circuit using such an optical detecting method has suffered from a problem of abnormal operation when the sensitivity thereof is decreased by strain in the lead tape and even slight changes in the luminosity of the sensor lamp. Also, the photo-transistor is generally placed in a special case for preventing ambient light from causing abnormal operation of the photo-transistor. As a result, extra space is necessary for the installation of the case, which inhibits the miniaturization of the video tape recorder (VTR).
Based on the above, it can be appreciated that there presently exists a need in the art for a tape terminus detection method and apparatus which overcomes the above-described shortcomings and disadvantages of the presently available tape terminus detection technology. The present invention fulfills this need.